Bending press

ABSTRACT

The invention relates to a bending press ( 1 ) for bending workpieces, comprising an upper tool ( 2 ) and a lower tool ( 3 ), a tool holder ( 4 ), in which the upper tool ( 2 ) is inserted, and a tool holder ( 5 ), in which the lower tool ( 3 ) is inserted, wherein the upper tool ( 2 ) and the lower tool ( 3 ) can be fixed in various positions within the respective tool holder ( 4, 5 ), a control device ( 13 ) for controlling the bending press ( 1 ), a sensor device ( 8 ), which is connected to the control device ( 13 ), and a stop ( 6 ) for positioning the workpiece within the bending press ( 1 ), wherein the stop ( 6 ) can be moved in relation to the tools ( 2, 3 ) by means of a drive ( 9 ) controlled by the control device ( 13 ). The sensor device ( 8 ) is designed to detect the position of the upper tool ( 2 ) and of the lower tool ( 3 ) within the bending press ( 1 ) without contact, and the control device ( 13 ) is designed to adapt the movement process by means of which the stop ( 6 ) is positioned in relation to the tools ( 2, 3 ), in dependence on the position of the upper tool ( 2 ) and of the lower tool ( 3 ) detected by means of the sensor device ( 8 ).

The invention relates to a bending press according to the preamble of claim 1 and a method for bending a workpiece using a bending press according to claim 8.

The selection and arrangement of workpieces in bending presses, also called press brakes or bending machines, is accomplished to a high degree manually and only partly assisted by the machine control. To this end, a bending plan is created which calculates the product-specific upper and lower tools and their theoretical position. However, there is no monitoring as to whether these tools are or were actually inserted into the machine. Furthermore, the tools can be introduced at positions which do not correspond to the process and comprise a potential hazard.

However, the exact position of the tools is required to perform high-quality bending sequences and to align the back stop fingers or a robot accordingly. A corresponding positioning is only possible by precise and work-intensive measurement by hand and transfer to the machine control.

Inaccurate positionings, non-allowance in the bending plan or an incorrect number of tools can result in damage to machine and peripheral. This is also possible as a result of an incorrect choice of tool geometry. Furthermore, upper and lower tools with maximum loads are defined—here also incorrect handling can result in damage. Damage caused by incorrect insertions on press brakes and tools can additionally lead to demands of any kind with respect to the manufacturer. Apparatuses are already known which attempt to solve the said problems in part but have a number of disadvantages. Thus, for example, a display device on the machine can merely predefine a desired position but not monitor and detect this.

JPH0952124A discloses a bending machine with upper and lower tool, a stop and a barcode reader which is disposed on the stop. Upper and lower tool are each provided with a barcode on their rear side which can be read out by the barcode reader. The barcode contains information about the condition of the tool. This information is transferred to an NC controller. In addition to the barcode reader, a contact sensor or end switch is provided on the stop by which of which the dimensions of the respective tool can be determined. Such a procedure is complex and time-consuming since the contact sensor must be moved several times and in different positions directly onto the tool.

With such a system, for example, tools on the outer sides of the machine cannot be detected since no (rear) stop can travel here as a result of the mechanism. In addition, only individually positioned tools can be detected. A plurality of tools pushed together (or arranged in a row) on a tool holder cannot be distinguished since the central tools cannot be detected by the known system as such. In particular, individually positioned tools can only be detected when the distances between the tools are sufficiently large in order that the rear stop or the fingers can travel in between. A barcode requires a relatively large amount of space so that such a barcode cannot be shown on very small punches (upper tool) [and] dies (lower tool). In addition, the detection of the barcode on sloping surfaces of the tool is very liable to error so that not all tools can be reliably detected. Also specially shaped tools cannot be detected if the rear stop cannot be moved mechanically between the tools. If the approximate position of the tool is not known before the detection process, there is a high risk of a collision with the rear stop. Since the workpieces to be processed also impact against the rear stop during positioning, the contact sensors are severely stressed and are easily damaged.

WO2012/103565A1 discloses a method for equipping a bending press with a bending tool. Here a controlled handling device with a gripper is used for the bending tool. A control device generates control commands in order to move the tool from an actual position into a desired position when inserting into the tool holder. Only when the tool has reached the desired position, is it inserted in the tool holder and fixed there. The tools held by the handling device must be approached directly by the (rear) stop in order to determine their actual position. The method is complex and based on the basic principle that the tools inside the tool holder must adopt an exact position so that the desired bending plan can be carried out.

EP0919300B1 (or DE69736112T2) discloses a bending machine in which the upper tools are provided with barcodes. A guide running in the Z direction for a scanner for reading the barcode is provided on the tool clamp for the upper tools on the side facing the operator. A linear scale, e.g. magnetic scale as position detection device is further provided on this tool clamp on the side facing the operator. The position data of the upper tools detected by the scanner are stored and made available again subsequently in a display. For producing the same product again, using the stored data the operator must place the tools precisely by hand according to the stored position. This bending machine is also based on the basic principle that the tools must adopt an exact position inside the tool holder so that the desired bending plan can be executed. However, the exact positioning and adjusting of the tool position requires high expenditure of time and personnel.

EP1517761B1 and DE602005005385T2 relate to special tools and tool holders which can detect tool positions relatively imprecisely by means of sensors. In this case, it is not possible in some cases to classify tools qualitatively and geometrically. In addition, the high acquisition costs of the required peripherals, the maintenance intensity, the necessary new acquisition of special punches and dies and their restricted geometry are disadvantages. Furthermore, as a result of the sensors introduced into the machine and tool, limiting pressing forces are to be expected. In addition, movable sensors on upper and lower beams as well as necessary data and supply cables reduce the variability of a press brake. The number of possible bending parts is limited.

EP1510267B1 (or DE69736962T2) discloses a method for displaying a tool arrangement in a press brake. On the basis of a displayed diagram it is determined whether the planned bending process is possible. Subsequently further tools are added for specific bending line sections and the process is repeated with the new arrangement. This process requires an exact positioning of the tools in the tool holder precisely as the previous method.

DE3830488A1 discloses an electronic tool recognition system for press brakes. By means of this system it is possible with the aid of an electronic control to recognize the built-in tool geometry, to protect the tools against overloading and ensure the working safety for the operator.

DE4442381A1 relates to an apparatus for position and shape recognition of upper beam tools on swivel bending machines and press brakes. Located behind the upper beam in a guide is a motor-displaceable slide on which a holder for a laser light curtain is mounted. With this the length of the built-in upper beam tools and their intermediate spaces are determined. The values are displayed numerically and graphically. In addition, a write-read head which reads out codes on the rear side of the upper beam tools is located in the holder.

All the known systems relate to the readout of codes and/or the detection of tool dimensions. The precise positioning of the tools inside the tool holder plays an essential role. In the prior art therefore it is necessary to position the tools exactly in relation to the tool holder which brings with it the disadvantage of a complex and time-intensive equipping of the bending machine

It is therefore the object of the present invention to eliminate the disadvantages of known solutions and provide a bending press in which an exact positioning of upper tool and lower tool is no longer required. Despite this, the entire bending process, including the positioning of the workpiece relative to the tools should be reliable and deliver bending parts exactly to bending plane.

The object is solved by the features of the independent claims.

According to the invention, the sensor device is configured to detect the position and/or the type of the upper tool and of the lower tool within the bending press without contact and the control device is configured to adapt the movement process by means of which the at least one stop is positioned relative to the tools depending on the position and/or type of the upper tool and the lower tool detected by means of the sensor device.

An important advantage of the invention consists in that the tools no longer need be positioned exactly within the tool holder when equipping the bending press. As a result expenditure of time and personnel can be saved. The invention is based on the principle that not the tools (or their position within the tool holder) are adapted to the bending plan but that the movement processes of the at least one stop are adapted to the position of upper and lower tool within the bending press or within the respective tool holder. As a result, a highly flexible system is created which automatically regulates the movement processes of the stop required before and during the bending process.

Initially the position of the tool already inserted into the tool holders is detected relative to the (or in) the tool holder. Depending on this relative tool position, an automatic adaptation of those movement processes with which the stop/stops (e.g. rear stops) is/are positioned is then made. A ‘non-exact’ insertion of the tool into the tool holder or an insertion at a completely different place is thereby automatically ‘compensated’ or taken into account. In fact, according to the invention there is no ‘incorrect’ insertion or positioning. Any arbitrary position of upper and lower tool in the tool holders results in an automatic adaptation of the stop control and a correct bending result. To this end, a bending program is stored in the control device which takes into account the position data of upper and lower tool detected by means of the sensor device as input quantity and generates control commands to the drive of the stop as output quantity depending on this input quantity.

‘Movement process of the stop’ or ‘movement of the stop’ is understood as any feasible movement of the stop in particular of its stop elements such as stop fingers and the like.

With the non-contact sensor device, in particular configured as a camera, a plurality of tools distributed along the Z axis and inserted in the tool holder could also be detected. An automatic determination of the gap width between two neighbouring upper or lower tools would also be feasible. If the coverage of the sensor device is sufficiently large, all the tools in a single holder can be recorded. In the case of smaller coverage, the camera can then be displaced so that the individual tools along the Z axis can be detected consecutively.

In one embodiment of the invention, the detection of the tool data can be made by means of the sensor device firstly independently or the position or of the presence at all of a (rear) stop. A stop could thus be mounted or inserted only after the detection step. In a further embodiment other or additional tool data could be detected which are not used to correct the stop but serve other purposes.

Preferably the at least one stop for positioning the workpiece is a rear stop which can be moved parallel to the bending line and that the sensor device is disposed in the region of the rear stop. At this point, the coverage of the sensor device is not disturbed by operating staff and workpieces to be inserted. Also this arrangement of the sensor device does not restrict the working range of the bending process. The sensor is additionally well-protected and as a result of its arrangement, can deliver reliable images of the rear side of the tools.

Preferably the sensor device is disposed on the stop, e.g. on the rear stop and can be moved together with the stop preferably parallel to the bending line. The axis of travel of the stop, e.g. rear stop is thereby used in two respects. In addition, other movement directions of the stop can also be controlled according to the invention (adapted to the position of the tools). The (rear) stop could, for example, be movable in three different spatial directions.

The arrangement of the sensor device, in particular in the form of a read head or a camera on a guide of the rear stop or directly thereon offers the following advantages: simple arrangement; no additional perturbing contours on the outer side of the machine; no hindrance of the bending process or personnel; the external appearance of the machine does not change for the user; the sensor device can be simply retrofitted and also allows the simultaneous read-off of upper tool (punch) and lower tool (die); the sensor device is protected with regard to contamination; a plurality of tools can be identified simultaneously along the Z axis; and the sensor device can be positioned arbitrarily. In addition, the position of the tools could also be calculated by means of the reference position of the rear stop along the Z axis.

Preferably the sensor device can be moved into a position in which the detection range of the sensor device covers both the upper tool and also the lower tool at least in part. As a result, all the required data can be recorded by means of a single measurement process or a single image recording. As a result of the large detection range, only one sensor device is required.

In a further embodiment the sensor device comprises at least two non-contact, in particular optical sensors with different spatial detection ranges. The movement of a sensor, e.g. along a bending line can thus be omitted. The detection ranges of the sensors can thereby overlap.

In a preferred embodiment, the bending press comprises an operator interface, in particular in the form of a screen, where sensor data of the sensor device and/or data derived from the sensor data can be presented on the operator interface (or output during operation automatically to the operator interface). It is preferable if the sensor device comprises at least one camera and the images or image sequences recorded by the camera are shown on the screen for the operator.

Preferably the sensor device is a camera, particularly preferably a matrix camera. Thus, not only codes or scales can be detected but—in particular when these are absent—the tool itself or its contours. Thus, a plurality of different information can be recorded by means of a single measurement/image recording.

Preferably a scale or a position marking is attached to the upper tool and/or the lower tool and/or the respective tool holder. This enables a reliable and exact determination of the relative position of tool to tool holder.

Preferably a two-dimensional code, in particular a data matrix code, is attached to the upper tool and/or the lower tool, wherein preferably the code contains information about the tool used, in particular about type and dimensions of the tool. Data matrix codes have some advantages for this application, for example, they allow a sloping read-off of the code. As a result—if the camera has a sufficiently large reading window—codes of upper tools and lower tools can be evaluated simultaneously. It is also possible to attach the code to sloping surfaces. Furthermore, the type of coding allows a relatively larger error tolerance, i.e. in the case of damage the code is still recognized. As already mentioned, extremely small code dimensions can also be read from a relatively large distance. Advantageously a code is attached to each of the front and the rear side of the tools in order to enable a detection of the corresponding tool even during rotation of the tool (mirrored introduction).

The object is also solved by a method for bending a workpiece using a bending press according to any one of the preceding embodiments. This process comprises the steps:

-   -   detecting the position and/or type of the upper tool and/or         lower tool which are fixed in the respective tool holders within         the bending press by means of the sensor device,     -   adapting the movement process by means of which the at least one         stop is positioned relative to the tools depending on the         position and/or type of the upper tool and/or lower tool         detected by means of the sensor device,     -   positioning the at least one stop according to the adapted         movement process by adjusting the stop by means of a drive         controlled by the control device relative to the tools,     -   performing a bending process by relative movement of upper tool         and/or lower tool.

This involves a flexible system which makes it possible to implement a specific bending plan independently of the position of the inserted tool. By adapting the controlled movement processes of the stop, the system is flexibly set to any tool position.

Preferably during the step of detecting the position and/or the type of upper tool and/or lower tool, its position relative to the respective tool holder in which the tool is fixed is detected. This is a particularly reliable method since due to the spatial proximity of tool and tool holder, these can easily be detected and recorded in one recording.

Preferably during the step of adapting the movement process a displacement path of the stop parallel to the bending line is calculated. The stop is as it were ‘tracked’ to the tool. The displacement path is here the output quantity whilst the position data of the tools constitute the input quantity of the bending program.

Preferably before and/or during the step of detecting the position and/or type of upper tool and/or lower tool, the sensor device is moved parallel to the bending line. As a result, tools can be detected in terms of position along the entire length of the bending press.

Preferably the position and/or the type of the upper tool and the position and/or the type of the lower tool are detected simultaneously. To this end, the detection range of the sensor device covers both upper tool and also lower tool or optionally their tool holders.

Preferably the position of the upper tool and/or the lower tool is detected with the aid of a scale or position marking attached to the upper tool and/or the lower tool and/or the respective tool holder. As a result, the accuracy of the position detection is increased. Size and shape of the tools can also be detected in relation to the scale or at a distance from the camera.

Preferably the detection of the position and/or detection of the type of upper tool and/or lower tool is made by a contour recognition of the tool. Here the position of the tool e.g. in relation to the (known) position of the sensor device can be determined independently of aids such as scales or codes. The camera is in a position to recognize the contours of the inserted tools and compare them with stored data (e.g. in the control device). If no data are stored or no codes are available at all, the tools are identified by means of their geometry and assigned accordingly.

Preferably the method comprises a step of reading out information of a two-dimensional code, in particular a data matrix code, applied to the upper tool and/or the lower tool. By using a data matrix code, it is also possible to mark extremely narrow tools.

The simultaneous identification of several codes is also possible due to the present invention. By linking the camera to the rear stop, the distance from the tools can be varied. According to the resolution of the camera, a plurality of codes and contours can thus be identified simultaneously.

The present idea is based on the fact that the inserted tools are identified in their position (optionally also in their type). The parameters thus determined are used via the machine control in such a manner that the peripheral equipment of the machine is adapted to the present bending process. Here, for example, mention should be made of the rear stop, it is then positioned in relation to the tools.

As a result, both the measurement and also the monitoring between an actual value and a desired value are saved—the tools can be inserted at any arbitrary position and the bending process can readily be started. Among other things, it is therefore no longer necessary to achieve exactly the same tool and workpiece positions for a recurring bending part. As mentioned, it is unimportant at which position the tools are located at all. By means of identification and conversion to the product, all relevant machine parts (stops) are positioned accordingly and at the same time a collision during the bending process is eliminated.

In a preferred embodiment, upper tool (punch) and lower tool (die) are identified simultaneously. The position of these tools with respect to one another can be safety-relevant and important for the quality of the bending. Safety-relevant means in this case that an incorrectly positioned upper tool can result in a collision. Thus, a monitoring between upper and lower tools corresponding to the bending process can be performed simultaneously. An incorrect insertion is thereby eliminated.

The invention also relates in one embodiment to the determination of type of tool and tool position of all upper tools (bending punches) and all lower tools (dies) within a bending press or bending machine.

In order to determine type of tool (including all its describing parameters) and exact Z-direction position in the bending process, 2D codes (preferably data matrix codes) and a read head should be used. For this purpose, the read head, preferably a matrix camera, is fastened to a Z-axis of the rear stop of the bending press, with the result that it is automatically adjustable. As a result of the relatively small dimensions of this camera and a cable chain already present on the axis, both installation and also the data transmission can easily be implemented.

In order to describe the parameters, a specific data matrix code is applied to each tool present. This code, for example, records a simple number which in the database can be assigned with the necessary parameters of the tool. This includes, for example: geometry, maximum load, material, number of bending cycles already performed, wear etc. By means of a description in terms of simple numbers, the data matrix codes can also be prepared in the smallest design and thus enable an application to extremely narrow tools (punch and dies).

A possible sequence could appear as follows. After introducing the tools into the bending press, upper tool (punch) and lower tool (dies) are clamped and are therefore now fixed in their position. Then the (matrix) camera travels with the Z axis over the entire length of the bending press. In so doing, depending on the reading speed of the camera, images of the tools are produced and evaluated by means of the machine control and database. The identification of the position of the inserted tools is made possible or simplified by a simple scale—attached to the tool clamping of the machine—preferably directly at or on the same height of the data matrix code. The scale is then part of the image produced and thus enables a precise determination of position.

Further advantages of preferred embodiments of the invention are listed hereinafter:

-   -   complete monitoring of the inserted tools     -   the bending plan can be converted automatically to real tool         positions     -   significantly shorter downtimes of the bending press during a         tool change since an exact measuring can be omitted,     -   the risk of overloading the bending press and tool is         significantly minimized,     -   compared to known solutions, extremely low-maintenance and         inexpensive,     -   all or different tools can be used (regardless of geometry,         manufacturer or type of clamping),     -   retrofitting of already existing tools is possible,     -   as a result of the non-contact measurement principle, the tools         are not restricted in their maximum loading,     -   contaminated or damaged codes are simply cleaned or re-applied,     -   no additional perturbing contours on the bending press or chains         for data cable,     -   the data matrix codes applied to the tools can simplify the         storage: also corresponding storage places or maximum usage         times of the tools or the like can be recorded in the         description of the code;     -   retrieving bending parts and programs: with the aid of the         (matrix) camera, codes can also be read from working plans or         sheets which for example stand for a certain sequence, a         corresponding program or a sheet quality.

In addition, the camera used can visualize the (rear) stop region. Frequently it is difficult to position sheets precisely at the rear stop fingers since the installation height of the bending press is too low or the inserted tools hinder the view of the stop fingers. To simplify the sequence, the camera image which shows the rear stop region can here be transferred to a screen visible for the operator.

Preferably it is displayed at an operator interface if the position of the upper tool and/or the lower tool detected by means of the sensor device is not correct, in particular if the tools are not aligned with one another. In this case, correction values relating to the positioning of upper tool and/or lower tool can be transferred to the control or the operator interface (e.g. image) in order to display to the operator that the tools are not aligned and the position of at least one tool must be corrected.

Preferably the bending process or the setting up process is interrupted if the position and/or type of the upper tool and/or the lower tool detected by means of the sensor device is not correct. In the case of incorrectly placed or incorrectly dimensioned tools, damage to the machine or hazards for the operating staff due to tool rupture can be eliminated in this way.

Preferably the method comprises a calibration of the position of the stop, wherein preferably the calibration is performed by means of a preferably optical position mark which is attached to a component of the bending press or to a reference tool. The calibration of the (rear) stop can be made in the X, R and Z direction by an optical reference (position marking) on the upper beam, on the tool clamp, within the bending press or by a reference tool so that an alignment of the (rear) stop by hand can be omitted if the stop has been shifted due to incorrect use.

Preferably the workpiece to be bent is provided with a read-out code which contains a reference to an appurtenant bending program and that after reading out the code preferably by means of the sensor device the appurtenant bending program is automatically loaded in the control device and/or executed. Thus, a loading of the bending program pertaining to the bending part into the control can be accomplished automatically by means of a code on the bending part (bending or sheet blank) in which the appurtenant bending program is encrypted. The code is, for example, applied to the bending part by means of a laser. The operator for example holds the sheet in front of the sensor device, e.g. a camera and the control automatically loads the corresponding program. The code can also be read out during positioning of the bending part on the stop, advantageously automatically by the sensor device.

Preferably the sensor device is a camera and the images or image sequences recorded with the camera are displayed at an operator interface. The transfer of the live camera image to the control or the operator interface enables the operator to display the actual situation inside the bending press.

This embodiment enables, inter alia:

-   -   operator guidance of the sheet before or during contact of the         sheet at the stop by means of camera image and faded-in guide         lines (similarly as during parking with a car);     -   operator guidance during insertion of the tools by means of         camera image and faded-in guide lines;     -   identification of contact of the sheet on the (rear) stop by         means of camera. (If the camera identifies that the sheet has         been correctly positioned on the stop, the control outputs a         corresponding signal and the operator can start the bending         process).     -   a monitoring of the machine space by the camera. This can be         used to monitor the approach speed of the stop to the table and         this can thus be moved faster than in conventional bending         processes.

A measurement of the bending of upper and lower beam can also be made with the sensor device. During the bending process upper and lower beam undergo a bending which can be compensated by camber cylinders. The crowning is calculated in the control by means of theoretical values and should be calculated in future by reference to the real state recorded by the sensor device. As a result, a higher accuracy can be achieved in the bent part.

The sensor device can also be configured to detect the (sheet) thickness of the inserted (sheet) workpiece. If the workpiece corresponds to the input data in the control device (machine control) or the corresponding values vary within the stipulated tolerance range, the bending process can be started or continued, otherwise the bending process can be discontinued or interrupted.

Likewise, workpiece or bending part dimensions (correct cutting, correct positioning) can be detected with the sensor device, thus enabling an improved operator guidance.

In a preferred embodiment, the specific method also comprises the creation of thermographic images of the bending press or of parts thereof. This is preferably accomplished by means of at least one IR sensor or at least one thermal image camera which can be disposed inside the bending press. Thus, the various heating states of the bending press (e.g. the tools, the machine frame etc.) can be monitored and evaluated. As a result of the heating, the machine body expands in an undefined manner in some cases which results in displacements of important reference points and therefore in inferior bending results. Particularly critical is an incompletely heated-through machine body, that is local temperature differences such as can occur, for example, directly after switching on the bending press. With the aid of the thermographic state images, individual reference axes can compensate for the displacements which occur and thus ensure a uniform bending quality.

Further advantages, features and details of the invention are obtained from the following description in which exemplary embodiments of the invention are described by reference to the drawings. In this case, the features mentioned in the claims and in the description can each be essential to the invention individually by themselves or in any combination.

The reference list is part of the disclosure. The figures are described cohesively and comprehensively. The same reference numbers means the same components, reference numbers with different indices indicate components which have the same function or are similar.

In the figures:

FIG. 1 shows a bending press according to the invention from the front,

FIG. 2 shows the bending press from FIG. 1 in side view,

FIG. 3 shows the bending press from FIG. 1 from behind,

FIG. 4 shows a detailed section of a bending press from the front, with upper and lower tool and the stop,

FIG. 5 shows an upper tool which is fixed in a tool holder,

FIG. 6 shows two lower tools which are fixed in a tool holder,

FIG. 7 shows a possible process sequence in the manner of a flow diagram,

FIG. 8 shows a schematic view of a bending press with control lines and travel paths and

FIG. 9 shows a schematic view of a link of the sensor device to an operator interface of the bending press.

FIG. 1 shows a bending press 1 for bending workpieces comprising an upper tool 2 (punch) and a lower tool 3 (die), a tool holder 4 in which the upper tool 2 is inserted and a tool holder 5 in which the lower tool 3 is inserted. The length of the tool holder 4, 5 along the Z axis, i.e. parallel to the bending line is so great that a plurality of upper and lower tools 2, 3 can be inserted and fixed adjacent to one another in the tool holder 4, 5. This case is shown in FIG. 6 where two lower tools 3 sit in the tool holder 5.

The upper tool 2 and the lower tool 3 can be fixed in various positions inside the respective tool holder 4, 5. That is, the tools can be arranged differently relative to the respective tool holder in the direction of the Z axis.

The bending press 1 has at least one stop 6 for positioning the workpiece 14 (FIG. 2) inside the bending press 1, where the stop 6 can be moved by means of a drive 9 controlled by a control device 13 (shown in FIG. 8) relative to the tools 2, 3. This movability relates in particular to a movability along the Z axis but a movability in other—in particular perpendicular thereto—spatial directions is also feasible. The exemplary embodiment from FIG. 1 shows two stops 6 which are movable independently of one another.

As can be seen from the side view of FIG. 2, in the present exemplary embodiment this recognizably comprises a rear stop, i.e. a stop which, when viewed from the operator side of the bending press 1, is located behind the tools 2, 3. The stop 6 serves to position the workpiece 14, e.g. a sheet to be bent, relative to the tools 2, 3. The rear stop is movable parallel to the bending line (along the Z axis). The sensor device 8 is located on the rear stop and can be moved together with the rear stop parallel to the bending line.

In an alternative embodiment, the sensor device 8 could be moved independently of the rear stop, e.g. sitting in its own holder. Preferably however the sensor device is disposed in the region of the rear stop.

In the embodiment shown, the stop 6 comprises stop fingers 7 which are additionally movable. Located next to the stop fingers 7 is a sensor device 8 based on a non-contact measurement principle, in particular in the form of a camera. The sensor device 8 is configured for non-contact detection of the position of the upper tool 2 and lower tool 3 inside the bending press 1. The stop 6 can be seen in detail in FIGS. 3 and 4.

In the embodiment described here, the sensor device 8 detects the position of the tools 2, 3 in the direction along the Z axis, i.e. along the bending line. This measurement can be made by detecting the position of a tool 2, 3 relative to the respective tool holder 4, 5 in which the tool 2, 3 is fixed.

FIG. 8 shows in schematic view the functional relationships in a bending press 1 according to the invention which also comprises a control device 13 for controlling the bending press 1. The control device 13 in particular controls the drive 12 for the upper tool 2 and therefore the actual pressing process. A further control line connects the control device 13 to the drive 9 for the stop 6. The sensor device 8 is also connected to the control device 13.

The control device 13 is now configured to adapt the movement process by means of which the at least one stop 6 is positioned relative to the tools 2, 3 depending on the position of the upper tool 2 and the lower tool 3 detected by means of the sensor device 8.

Two possible positions of upper tool 2 and lower tool 3 are shown as an example, one of which is shown by a dashed line. For the first position (continuous line) a travel path z₁ is calculated as a function of the position in order to align the stop 6 in relation to the tools 2, 3. In this case, —as shown—the stop 6 need not necessarily come to rest behind the tool but other positions relative to the tool are also feasible according to the bending plan.

For the second position (dashed line) a travel path z₂ is calculated as a function of the position in order to align the stop 6 in relation to the tools. By means of this position the approach coordinates of the stop 6 are adapted to the respective position of the tool so that a corresponding bending process can be executed according to the bending plan. The adapting or adaptation of the movement process can naturally also relate to the movements of the stop fingers 7.

Also—as indicated in FIG. 6—a plurality of tools can sit in one tool holder whereby a plurality of bending line sections are defined. The bendings associated therewith can be transferred simultaneously or consecutively to the workpiece. In this case, the approach coordinates of the stop 6 are adapted automatically.

The method for bending a workpiece with a bending press 1 can now comprise the following steps which are shown in the flow diagram of FIG. 7:

Step 20: equipping the bending press with at least one upper tool and/or at least one lower tool which is/are fixed within the respective tool holder.

Step 21: detecting the position of the upper tool 2 and/or lower tool 3 which are fixed in the respective tool holders 4, 5 within the bending press 1 by means of the sensor device 8. For example, the sensor device 8 can be moved parallel to the bending line (i.e. along the Z axis) before and/or during the step 21.

Step 22: adapting the movement process by means of which the at least one stop 6 is positioned relative to the tools 2, 3 depending on the position of the upper tool 2 and/or lower tool 3 detected by means of the sensor device 8. This step can be accomplished, for example, by calculating a travel path z₁, z₂ of the stop 6 parallel to the bending line (i.e. along the Z axis).

Step 23: positioning the at least one stop 6 according to the adapted movement process by moving the stop 6 by means of a drive 9 controlled by the control device 13 relative to the tools 2, 3.

Step 24: performing a bending process by relative movement of upper tool 2 and/or lower tool 3.

Step 25: exchanging and/or adding upper and/or lower tools and the fixing thereof in the respective tool holder.

Steps 21 to 25 can then be repeated.

Preferably the position of the upper tool 2 and the position of the lower tool 3 located at the same height are detected simultaneously. To this end, the sensor device 8 can be moved into a position in which the detection range of the sensor device 8 covers both the upper tool 2 and also the lower tool 3 at least partially.

FIGS. 5 and 6 show preferred variants of the invention in which a scale 10 is applied to the respective tool holder 4, 5. Alternatively or additionally a scale could also be applied to the upper tool 2 and/or the lower tool 3.

In this embodiment, the detecting or the detection of the position of the upper tool 2 and/or the lower tool 3 can be made with the aid of a scale 10. To this end, image recordings of the sensor device 8 configured as a camera are evaluated in view of the relative position of the tool in relation to the scale (e.g. by using appropriate image recognition software). As can be seen from FIGS. 5 and 6, the scale division extends parallel to the bending line.

Preferably the detection of the position of the upper tool 2 and/or the lower tool 3 is made by contour recognition of the tool 2, 3 by means of appropriate image processing programs.

In a preferred variant, a two-dimensional code 11, in particular a data matrix code (comprising an arrangement of black and white rectangles inside a field) is applied to the upper tool 2 and the lower tool 3. The code 11 contains information about the tool 2, 3 used, in particular about type and dimensions of the tool 2, 3.

Advantageously one code 11 each is applied to the front side and to the rear side of a tool 2, 3. Consequently, the tool 2, 3 can also be inserted in a mirror-inverted manner into a tool holders 4, 5 and detected simply by the sensor device 8.

In this embodiment, the code information can also be read out by means of the sensor device 8. It can subsequently be checked whether a tool complies with predefined specifications or is compatible with the bending plan.

FIG. 9 shows an embodiment in which the sensor device comprises two non-contact sensors with different spatial detection ranges. The sensors here are optical sensors, in particular cameras. The cameras image different regions along the bending line Z (also called Z axis). The detection ranges of the sensors can overlap in this case.

It can furthermore be seen from FIG. 9 that the bending press comprises an operator interface 27 (here in the form of a screen) which is connected to the control device 13 or the sensor device 8. Here sensor data of the sensor device 8 and/or data derived from the sensor data can be shown on the operator interface 27. These data can be output automatically to the operator interface 27 during operation.

The sensor device 8 can also comprise only one sensor or camera. In particular, the images or image sequences recorded with the camera can be displayed on the operator interface 27.

In a preferred method it can be displayed on the operator interface 27 when the position of the upper tool 2 and/or lower tool 3 detected by means of the sensor device 8 is not correct, in particular when the tools 2, 3 are not aligned with one another. As a result of this information, which can already contain correction values, it is possible for the operator to correct the position of the tools 2, 3 in a simple manner.

The invention is not restricted to the described embodiments and the aspects emphasized therein. On the contrary, a multiplicity of modifications are possible within the inventive idea which lie within the framework of technical action. It is also possible to achieve further embodiments by combining the said means and features without departing from the framework of the invention.

REFERENCE LIST

-   1 Bending press -   2 Upper tool -   3 Lower tool -   4 Tool holder for upper tool 2 -   5 Tool holder for lower tool 3 -   6 Stop -   7 Stop finger -   8 Sensor device -   9 Drive for stop 9 -   10 Scale -   11 Code -   12 Drive for upper tool 2 -   13 Control device -   14 Workpiece -   20-26 Process steps -   27 Operator interface -   Z Bending line 

1-20. (canceled)
 21. Bending press (1), in particular brake press, for bending workpieces (14) comprising, an upper tool (2) and a lower tool (3), a tool holder (4) in which the upper tool (2) is inserted and a tool holder (5) in which the lower tool (3) is inserted, wherein the upper tool (2) and the lower tool (3) can be fixed in different positions within the respective tool holder (4, 5), a control device (13) for controlling the bending press (1), a sensor device (8) which is connected to the control device (13), at least one stop (6) for positioning the workpiece inside the bending press (1), wherein the stop (6) can be moved relative to the tools (2, 3) by means of a drive (9) controlled by means of the control device (13), characterized in that the sensor device (8) is configured for detecting the position and/or the type of the upper tool (2) and lower tool (3) inside the bending press (1) without contact, and the control device (13) is configured to adapt the movement process by means of which the at least one stop (6) is positioned relative to the tools (2, 3) depending on the position and/or type of the upper tool (2) and the lower tool (3) detected by means of the sensor device (8).
 22. The bending press according to claim 21, characterized in that the at least one stop (6) for positioning the workpiece is a rear stop which can be moved parallel to the bending line and that the sensor device (8) is disposed in the region of the rear stop.
 23. The bending press according to claim 21, characterized in that the sensor device (8) is disposed on the stop (6) and can be moved together with the stop (6) preferably parallel to the bending line.
 24. The bending press according to claim 21, characterized in that the sensor device (8) can be moved into a position in which the detection range of the sensor device (8) covers both the upper tool (2) and also the lower tool (3) at least in part.
 25. The bending press according to claim 21, characterized in that the sensor device (8) is a camera.
 26. The bending press according to claim 21, characterized in that a scale (10) or a position marking is attached to the upper tool (2) and/or the lower tool (3) and/or the respective tool holder (4, 5).
 27. The bending press according to claim 21, characterized in that a two-dimensional code (11), in particular a data matrix code, is attached to the upper tool (2) and/or the lower tool (3), wherein preferably the code (11) contains information about the tool (2, 3) used, in particular about type and dimensions of the tool (2, 3).
 28. Method for bending a workpiece (14) using a bending press (1) according to claim 21, characterized by the steps of: detecting the position and/or type of the upper tool (2) and/or lower tool (3) which are fixed in the respective tool holders (4, 5) within the bending press (1) by means of the sensor device (8), adapting the movement process by means of which the at least one stop (6) is positioned relative to the tools (2, 3) depending on the position and/or type of the upper tool (2) and/or lower tool (3) detected by means of the sensor device (8), positioning the at least one stop (6) according to the adapted movement process by adjusting the stop (6) by means of a drive (9) controlled by the control device (13) relative to the tools (2, 3), performing a bending process by relative movement of upper tool (2) and/or lower tool (3).
 29. The method according to claim 28, characterized in that during the step of detecting the position and/or the type of upper tool (2) and/or lower tool (3), its position relative to the respective tool holder (4, 5) in which the tool (2, 3) is fixed is detected.
 30. The method according to claim 28, characterized in that during the step of adapting the movement process a displacement path (z1, z2) of the stop (6) parallel to the bending line is calculated.
 31. The method according to claim 28, characterized in that before and/or during the step of detecting the position and/or type of upper tool (2) and/or lower tool (3), the sensor device (8) is moved parallel to the bending line.
 32. The method according to claim 28, characterized in that the position and/or the type of the upper tool (2) and the position and/or the type of the lower tool (3) are detected simultaneously.
 33. The method according to claim 28, characterized in that the position of the upper tool (2) and/or the lower tool (3) is detected with the aid of scale (10) or position marking attached to the upper tool (2) and/or the lower tool (3) and/or the respective tool holder (4, 5).
 34. The method according to claim 28, characterized in that the detection of the position and/or detection of the type of upper tool (2) and/or lower tool (3) is made by a contour recognition of the tool (2, 3).
 35. The method according to claim 28, characterized in that the method comprises a step of reading out information of a two-dimensional code (11), in particular a data matrix code, applied to the upper tool (2) and/or the lower tool (3).
 36. The method according to claim 28, characterized in that it is displayed at an operator interface (27) if the position of the upper tool (2) and/or the lower tool (3) detected by means of the sensor device (8) is not correct, in particular if the tools (2, 3) are not aligned with one another.
 37. The method according to claim 28, characterized in that the bending process or the setting up is interrupted if the position of the upper tool (2) and/or the lower tool (3) detected by means of the sensor device (8) is not correct.
 38. The method according to claim 28, characterized in that the method includes a calibration of the position of the stop (6), wherein preferably the calibration is performed by means of a preferably optical position mark which is attached to a component of the bending press (1) or to a reference tool.
 39. The method according to claim 28, characterized in that the workpiece (14) to be bent is provided with a read-out code which contains a reference to an appurtenant bending program and that after reading out the code preferably by means of the sensor device (8) the appurtenant bending program is automatically loaded in the control device (13) and/or executed.
 40. The method according to claim 28, characterized in that the sensor device (8) comprises at least one camera and the images or image sequences recorded with the camera are displayed at an operator interface (27). 